Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

The present invention relates to an oil-in-water (O/W) type nano-emulsion
composition comprising an oil component containing oil and a polyethylene
glycol ester-based emulsifier; and a water component containing a polyol
or a polyol derivative. The present invention also relates to a cosmetic
composition comprising the oil-in-water type nano-emulsion composition,
and to a method for preparing the oil-in-water type nano-emulsion
composition. According to the present invention, a nano-sized
low-viscosity emulsion having a high inner phase can be obtained through
the method that is different from the conventional methods of phase
inversion temperature emulsification or high pressure emulsification,
thereby significantly improving the stability of the emulsion. In
addition, the nano-emulsion composition of the present invention can be
added to a variety of cosmetic compositions having a variety of methods
of use and can thus deliver active ingredients to the skin effectively
since it has small-sized particles.

Claims:

1. An oil in water (O/W) type nanoemulsion composition comprising: an oil
phase component comprising oil and a polyethylene glycol ester-based
emulsifier; and an aqueous phase component comprising a polyol or polyol
derivative.

2. The composition according to claim 1, wherein the nanoemulsion has a
viscosity of 0-4000 cps.

3. The composition according to claim 1, wherein the nanoemulsion has an
average particle size of 10-500 nm.

4. The composition according to claim 1, wherein the nanoemulsion is
white-colored.

5. The composition according to claim 1, wherein the polyethylene glycol
ester-based emulsifier is a PEG-n glyceryl isostearate having a
polymerization degree of 3-90.

6. The composition according to claim 1, wherein the polyethylene glycol
ester-based emulsifier is present in an amount of 0.1-10 wt % based on
the total weight of the composition.

7. The composition according to claim 1, wherein the oil is at least one
selected from the group consisting of silicone oil, ester-based oil,
hydrocarbon-based oil and a mixture thereof.

8. The composition according to claim 7, wherein the oil is at least one
selected from the group consisting of triethylhexanoin, dimethicone,
cetyl octanoate, dicaprylate/dicaprate, isopropyl miristate, tocopherol
acetate and caprylic/capric triglycerides.

9. The composition according to claim 1, wherein the oil is present in an
amount of 1-20 wt % based on the total weight of the composition.

10. The composition according to claim 1, wherein the polyol or polyol
derivative comprises at least one selected from the group consisting of
glycerin, monohydric or dihydric alcohol and a mixture thereof.

11. A cosmetic composition comprising the composition as defined in claim
1.

12. A method for preparing an O/W type nanoemulsion composition,
comprising: heating an oil phase component comprising oil and a
polyethylene glycol ester-based emulsifier; heating a polyol or polyol
derivative; introducing the oil phase component to the polyol or polyol
derivative to form an oil in polyol (O/P) type gel; adding an aqueous
phase component to the O/P type gel, followed by agitation; and cooling
the agitated components.

13. The method for preparing an O/W type nanoemulsion composition
according to claim 12, wherein the polyethylene glycol ester-based
emulsifier is a PEG-n glyceryl isostearate having a polymerization degree
of 3-90.

Description:

TECHNICAL FIELD

[0001] This disclosure relates to a nano-sized low-viscosity oil-in-water
type emulsion composition, a cosmetic composition comprising the same,
and a method for preparing the same using an oil-in-polyol (O/P) type
emulsification method.

BACKGROUND ART

[0002] Emulsion means a liquid-liquid dispersion system having a liquid
phase in which at least one liquid phase immiscible with the former
liquid phase is dispersed, and generally has a size distribution ranging
from several micrometers to several tens micrometers.

[0003] Macroemulsion having such a particle size is in a thermodynamically
unstable state, and tends to undergo separation by way of various paths
such as flocculation, sedimentation, creaming, Ostwald ripening and
coalescence.

[0004] When the emulsion particle size of a dispersed phase is lowered to
a nano-scale, it is possible to improve the emulsion stability
significantly in terms of kinetics through the Brownian movement among
the particles, and to produce a low-viscosity emulsion having a high
inner phase content. As a result, it is possible to provide a cosmetic
agent having various feelings of use and to deliver active ingredients
effectively to skin by virtue of such a small particle size.

[0005] In general, although there is a slight difference among various
references, a liquid-liquid dispersion system in which particles of a
dispersed phase has an average particle diameter of 20-500 nm is referred
to as nanoemulsion (Flockhart, I. R. etc., Nanoemulsions derived from
lanolin show promising drug delivery properties, J. Pharm. Pharmacol., 50
(Supplement) 1998, 141).

[0006] Many attempts have been made to produce a nanoemulsion having fine
particles and low viscosity. Particularly, a phase inversion temperature
(PIT) emulsification method or a high-pressure emulsification method has
been used.

[0007] More particularly, a PIT emulsification method is one using the
principle of hydrophilicity reduction in a ternary composition of water,
oil and a non-ionic surfactant through a decrease in hydrogen bonding
between ethylene oxide as a hydrophilic group of the non-ionic surfactant
and water according to an increase in temperature. Herein, the ternary
composition forms an O/W type emulsion below a specific temperature and
forms a W/O type emulsion above a specific temperature. Such a specific
temperature is called a PIT.

[0008] In addition, a high-pressure emulsification method is one including
passing particles through a high-pressure emulsifier to which high shear
is applied at 1000-1500 atm to provide nanoparticles. As a high-pressure
emulsifier, a microfluidizer (U.S. Pat. No. 4,533,254) capable of
application of a pressure of 1000 atm or higher is frequently used.

[0009] As described above, various attempts have been made to provide fine
and uniform particles. However, they are limited technically in terms of
viscosity, nano-sized particle formation, maximization in visual effects
of white-colored cosmetic agents or cost, and thus cosmetic producers
have many difficulties in making unlimited prescriptions. In fact, the
methods according to the related art cannot find use for commercial
production.

[0010] Under these circumstances, many studies have been conducted to
overcome the above-mentioned technical limitation and to provide a
nano-sized low-viscosity emulsion.

DISCLOSURE

Technical Problem

[0011] This disclosure is directed to providing a low-viscosity
white-colored oil-in-water (O/W) type nanoemulsion composition, which,
otherwise, cannot be obtained according to the prior art, and a cosmetic
composition comprising the same. This disclosure is also directed to
solving the problems of the high-pressure emulsification method or phase
inversion temperature (PIT) emulsification method used for producing an
O/W type nanoemulsion composition according to the prior art, and to
providing a novel method different therefrom.

Technical Solution

[0012] In one general aspect, there is provided an oil-in-water (O/W) type
nanoemulsion composition, comprising: an oil phase component comprising
oil and a polyethylene glycol ester-based emulsifier; and an aqueous
phase component comprising a polyol or polyol derivative.

[0013] In another general aspect, there is provided a cosmetic composition
including the nanoemulsion composition.

[0014] In still another general aspect, there is provided a method for
preparing an O/W type nanoemulsion composition, comprising: heating an
oil phase component containing oil and a polyethylene glycol ester-based
emulsifier; heating a polyol or polyol derivative; introducing the oil
phase component to the polyol or polyol derivative to form an oil in
polyol (O/P) type gel; adding an aqueous phase component to the O/P type
gel, followed by agitation; and cooling the agitated components.

Advantageous Effects

[0015] The nano-sized low-viscosity emulsion having a high inner phase
content can be obtained through the method that is different from the
conventional methods of phase inversion temperature emulsification or
high pressure emulsification, thereby significantly improving the
stability of the emulsion. In addition, the nano-emulsion composition can
be applied to a variety of cosmetic compositions, and can produce
cosmetic compositions having a variety of feelings of use. Further, the
nano-emulsion composition has small-sized particles, and thus can deliver
active ingredients to the skin effectively.

BEST MODE

[0016] According to one embodiment, the emulsion is not particularly
limited as long as it has such a low viscosity that a desired degree of
dispersibility can be obtained to increase the inner phase content and to
deliver active ingredients effectively. For example, the emulsion may
have a viscosity of 4000 cps or lower, particularly 2000 cps or lower,
and more particularly 1000 cps or lower. The term `low-viscosity`
emulsion covers any emulsion from one having too low viscosity to measure
it experimentally to one having the above-defined range of viscosity.
When the viscosity cannot be measured experimentally, the viscosity is
defined as 0. Thus, for example, the emulsion may have a viscosity of 0
to 4000 cps, particularly 1 to 2000 cps, and more particularly 5 to 1000
cps.

[0017] According to another embodiment, the emulsion is not particularly
limited as long as it has a nano-scaled size and allows production of a
low-viscosity emulsion while improving the emulsion stability. For
example, the emulsion may have an average size of 500 nm or less,
particularly 300 nm or less. For example, although the emulsion may have
any average size within the above-defined range, it may have an average
size of 10-500 nm, particularly 50-300 nm.

[0018] The emulsion may have a very narrow particle size distribution of
10-800 nm, particularly 100-600 nm. By virtue of this, it is possible to
provide a nanoemulsion composition having a fresh feeling of use as well
as excellent stability.

[0019] According to still another embodiment, the emulsion composition may
be white-colored, particularly may be white-colored and creamy. When a
nanoemulsion is prepared by the conventional phase inversion temperature
(PIT) emulsification method as described in the following Comparative
Example 2, the resultant nanoemulsion may have a translucent bluish
appearance, but cannot realize a white-colored and creamy appearance. On
the contrary, the emulsion composition disclosed herein may provide a
visual effect through a white-colored, particularly white-colored and
creamy, highly concentrated appearance.

[0020] The composition disclosed herein comprises oil and a polyethylene
glycol ester-based emulsifier as an oil phase component, and polyol or a
polyol derivative as an aqueous phase.

[0021] According to an embodiment, the polyethylene glycol ester-based
emulsifier is not particularly limited as long as it is used generally in
preparation of O/W type emulsion compositions. For example, the
polyethylene glycol ester-based emulsifier may be a PEG-n glyceryl
isostearate having a polymerization degree of 3-90, particularly 3-60. In
addition, two or more PEG-n glyceryl isostearates having different
polymerization degrees may be used in combination, for example, at a
mixing ratio of 1-5:1 to 1:1-5, particularly 1-3:1 to 1:1-3.

[0022] The emulsifier may be present in an amount of 0.1-20 wt,
particularly 0.1-10 wt, based on the total weight of the composition.
When the emulsifier is used in an amount greater than 10 wt, the oil
phase becomes have an inadequate combination ratio, resulting in
excessively high viscosity. When the emulsifier is used in an amount less
than 0.1 wt, emulsifying capability is lowered and emulsion particles
having an excessively large particle size are formed, resulting in
degradation of the emulsion stability.

[0023] According to an embodiment, the oil is not particularly limited in
type as long as it is generally used in preparation of O/W type emulsion
compositions. For example, the oil may be at least one selected from the
group consisting of silicone oil, ester-based oil, hydrocarbon-based oil
and a mixture thereof.

[0024] For example, the oil selected from the group consisting of silicone
oil, ester-based oil, hydrocarbon-based oil and a mixture thereof may be
at least one selected from the group consisting of triethyihexanoin,
dimethicone, cetyl octanoate, a mixture of dicaprylate with dicaprate,
isopropyl miristate, tocopherol acetate and a mixture of caprylic
triglyceride with capric triglyceride.

[0025] The oil may be present in an amount of 0.1-40 wt, particularly 1-20
wt based on the total weight of the composition. The `oil content` means
the total amount of the components forming the oil phase free from an
emulsion stabilizer. When the oil is used in an amount less than 1 wt,
the resultant composition shows a decrease in moisturizing and emollient
feelings, thereby reducing utility. When the oil is used in an amount
greater than 20 wt, the emulsion particles become have an increased
particle size, resulting in degradation of the emulsion stability.

[0026] If desired, the composition disclosed herein may further include a
pigment, fragrance, preservative or thickening agent as supplementary
components for use in preparation of O/W type nanoemulsion compositions.
Such supplementary components may be used in an amount of 0-20 wt based
on the total weight of the composition.

[0027] The polyol or polyol derivative is an aqueous phase component, and
any polyol or derivative thereof may be used as long as it is suitable
for preparation of low-viscosity nanoemulsion. For example, the polyol or
polyol derivative may be at least one selected from the group consisting
of glycerin, monohydric or dihydric alcohol and a mixture thereof.
Particularly, the polyol or polyol derivative contained in the
composition disclosed herein may be a mixture of glycerin with butylene
glycol as a dihydric alcohol, but is not limited thereto.

[0028] In another aspect, there is provided a cosmetic composition
including the nanoemulsion composition.

[0029] The cosmetic composition disclosed herein is not particularly
limited in its formulation. For example, the cosmetic composition may be
one applied to skin, mucous membranes, scalp or hair. Particularly, the
cosmetic composition may be formulated into fundamental cosmetics such as
skin softener, nourishing milk, lotion, cream, pack, gel, patch or spray
(mist); make-up cosmetics such as lipsticks, make-up base or foundation;
cleaning agents such as shampoo, rinse, body cleanser, tooth paste or
mouth wash; hair treatment such as hair tonic, gel or mousse; or hair
cosmetic compositions such as hair nutrient or hair dye. In addition, the
cosmetic composition may be applied widely to medicines and
over-the-counter medicines, such as lotion, ointment, gel, cream, patch
or spray.

[0030] In still another aspect, there is provided a method for preparing
an O/W type nanoemulsion composition, comprising: heating an oil phase
component comprising oil and a polyethylene glycol ester-based
emulsifier; heating a polyol or polyol derivative; introducing the oil
phase component to the polyol or polyol derivative to form an oil in
polyol (O/P) type gel; adding an aqueous phase component to the O/P type
gel, followed by agitation; and cooling the agitated components.

[0031] According to the prior art, a general emulsification method in
which an oil phase component and aqueous phase component are heated and
agitated was used to prepare a nanoemulsion composition. However, such a
method results in poor shelf stability and causes skin irritation due to
an increased amount of surfactant, and thus cannot be used in practice.
In addition, to solve the problem related with shelf stability, a water
soluble polymer such as a carboxyvinyl polymer was used so that the
emulsion stability was ensured. However, in this case, the emulsion shows
an excessively high viscosity of 5000 cps or higher. Therefore, such a
method does not allow formulation of emulsion.

[0032] In addition to the above method, a phase inversion temperature
(PIT) emulsification method was used. However, a polyoxyethylene
(POE)-based compound used generally as a non-ionic surfactant in such a
PIT emulsification method provides a low PIT of approximately room
temperature to 60° C., resulting in degradation of stability. In
the case of cosmetics, they may undergo an increase in temperature during
storage or transport, or may be stored or distributed in a hot place.
Thus, an O/W type nanoemulsion may be unstabilized and undergo phase
separation easily at a low PIT. Moreover, the PIT emulsification method
provides nanoparticles with a translucent bluish appearance, and cannot
realize a white-colored or milky white and highly concentrated
appearance.

[0033] Further, a high-pressure emulsification method was used but it
requires a big space, long time and expensive equipment. Thus, the method
is limited in use in terms of cost. In addition, the method using a
high-pressure emulsifier is applied to an emulsification system for milky
liquid or cream having a high oil content. However, it is difficult to
apply the method to a system having a little of or no oil, such as skin
milk.

[0034] To solve the problems occurring in the related art, the method
disclosed herein provides an O/W type nanoemulsion by using a
polyethylene glycol ester-based emulsifier according to an oil in polyol
(O/P) type emulsification method. By virtue of this, it is possible to
provide an O/W type nanoemulsion to composition having low viscosity, a
very small average particles size of emulsion particles, excellent
stability and a highly concentrated white-colored creamy feeling.

[0035] The examples and experiments will now be described. The following
examples and experiments are for illustrative purposes only and not
intended to limit the scope of this disclosure.

Comparative Examples 1-3 and Example 1

[0036] Each O/W type emulsion or nanoemulsion of Comparative Examples 1-3
and Example 1 is prepared by using the compositions as shown in the
following Table 1 according to each of the methods described herein (The
percentage described hereinafter is by weight).

<Preparation of Comparative Example 1>

[0037] 1) Oil phase components and aqueous phase components are warmed
separately to 75° C. [0038] 2) The oil phase components are
introduced to the aqueous phase components with stirring and the
resultant mixture is agitated by using a homogenizer at 3000 rpm for 5
minutes. [0039] 3) Then, the mixture is cooled and deaerated gradually.

<Preparation of Comparative Example 2>

[0039][0040] 1) Oil phase components are mixed and warmed to a
temperature 20° C. higher than the expected phase inversion
temperature to dissolve them completely. [0041] 2) Aqueous phase
components are mixed and dissolved, and then warmed to the same
temperature as the oil phase components. [0042] 3) The aqueous phase
components (2)) are added gradually to the oil phase components (1))
while agitating them by using a homogenizer at 2000 rpm to perform
emulsification, thereby providing a W/O emulsion. [0043] 4) Then, the
emulsion is cooled gradually with stirring to perform phase inversion
into an O/W type. [0044] 5) After determining the phase inversion, a
thickener and other additives are introduced, followed by agitation.
[0045] 6) After the emulsion is agitated completely, it is deaerated and
cooled to 30° C. to finish the emulsion.

<Preparation of Comparative Example 3>

[0045][0046] 1) Oil phase components and aqueous phase components are
warmed separately to 75° C. [0047] 2) The oil phase components are
introduced to the aqueous phase components with stirring and the
resultant mixture is agitated by using a homogenizer at 3000 rpm for 5
minutes. [0048] 3) Nanoparticles are formed from the homogenized mixture
by using a microfluidizer (U.S. Pat. No. 4,533,254) at 1000 atm. [0049]
4) The nanoparticles are cooled and deaerated gradually.

<Preparation of Example 1>

[0049][0050] 1) Oil phase components are heated to 75° C. [0051]
2) A polyol (glycerin, butylene glycol) as one of aqueous phase
components is heated to 75° C. [0052] 3) The oil phase components
are introduced to the component (2)) with stirring, and the resultant
mixture is agitated by using a homogenizer at 3000 rpm for 5 minutes to
form an O/P type translucent gel. [0053] 4) The remaining aqueous phase
components are introduced to the gel (3)) and the resultant mixture is
agitated by using a homogenizer at 2500 rpm for 3 minutes, [0054] 5)
followed by gradual cooling and deaeration.

[0055] Each O/W type emulsion or nanoemulsion according to Comparative
Examples 1-3 and Example 1 is determined for particle size, appearance
and viscosity during preparation, and the results are shown in the
following Table 2.

[0056] Referring to the results of Table 2, it can be seen that
Comparative Examples 2 and 3 (except Comparative Example 1) and Example 1
provide a low-viscosity nanoemulsion having a desired viscosity of 1000
cps or less and a particle size of 500 nm or less. In terms of
appearance, Comparative Example 1 and Example 1 provide a desired
white-colored emulsion.

Test Example 2

Determination of Emulsion Stability

[0057] Each O/W type cosmetic agent according to Comparative Examples 1-3
and Example 1 is used as a test sample, and determined for emulsion
stability by observing whether creaming or oil separation occurs or not
while each emulsion is stored at room temperature, at 45° C. and
in a circulating thermostat bath for 5 days, 10 days, 15 days and one
month. The results are shown in the following Table 3.

TABLE-US-00003
TABLE 3
Comp.
Comp. Ex. 1 Comp. Ex. 2 Ex. 3 Ex. 1
Room 5 days good good good good
Temperature 10 days good good good good
(RT) 15 days good creaming creaming good
1 month good creaming creaming good
45° C. 5 days good good good good
10 days good creaming good good
15 days good creaming creaming good
1 month creaming oil oil good
separation separation
Circulating 5 days good good good good
theremostat 10 days good good good good
15 days good creaming creaming good
1 month good creaming creaming good

[0058] As can be seen from Table 3, the O/W nanoemulsion according to
Example 1 ensures higher stability at room temperature, at a high
temperature and in a circulating condition, as compared to the O/W type
emulsions according to Comparative Examples 1-3. In other words, it is
possible to obtain a stable nano-sized low-viscosity O/W type
white-colored emulsion by using an oil in polyol (O/P) emulsification
method in the preparation an O/W type nanoemulsion.

[0059] While the exemplary embodiments have been shown and described, it
will be understood by those skilled in the art that various changes in
form and details may be made thereto without departing from the spirit
and scope of this disclosure as defined by the appended claims.